This invention concerns conveyor belts, especially helical, so-called spiral conveyor belts, and embraces a method and apparatus for adding one or more intermediate support rails to an existing spiral conveyor belt system with or without removal of the belt from the existing support apparatus, or the disassembly of the spiral conveyor belt system.
Spiral conveyor belts have been in increasing use in various industries, particularly where a somewhat lengthy dwell time in a certain area or in a certain environment is needed. These include plastic modular conveyor belt systems, such as shown in U.S. Pat. Nos. 4,901,844 and 6,484,379, used for many purposes, but very commonly for transporting food articles. Bakery goods, for example, are often carried on plastic spiral conveyor belts, giving a desired dwell time for rising or for baking. These belts, however, particularly plastic spiral conveyor belts, are increasingly being used for other, non-food applications.
Often the belts are subjected to increased loading, sometimes across a wide spiral belt, such as 30 inches or more in width. Support for a spiral belt typically is provided by structure just outside the outer edge of the belt tiers, such as columns spaced around the circumference of the helical belt, these columns supporting cantilevered rods extending inwardly under the belt at intervals forming a helical path.
Often a belt subjected to heavier than usual loading needs additional support under the belt. Typically, metal spiral belts run on two parallel support rails, capped with wear strip, relying on the inherent rigidity of the metal structure and metal rods to prevent the belt from sagging in the middle under load. Modular plastic spiral belts typically use plastic rods and lack the rigidity of metal. Consequently, plastic belts in particular can sag in the middle under a product load. One of two things is presently done to alleviate the sagging problem: the original spiral conveyor manufacturer is contracted to install a permanent third support rail (very expensive and time-consuming), or steel rods are installed in the belt either every row or at determined spacing (adds weight to the belt and defeats much of the value of the plastic belt). Often only two wear strip support rails are provided, one near the inner edge of the belt and one near the outer edge. With increased load near the middle of the belt, there is often a need for further support rails with wear strips, at one or two locations intermediate to the outer support rails. Once the belt has been removed, and a substantial portion of the system has been dismantled, a large, time-consuming and expensive undertaking, a technician secures further support rails onto the cantilevered support rods, using the same securing hardware as with the existing support rails. When this has been accomplished, the belt must be replaced on the helical support path and much of the system must be reassembled.
There has been a need for a technique and accompanying apparatus which would enable additional rail supports to be added to a spiral conveyor belt support structure quickly and less expensively than installing a third rail in the same manner as the original rail installation. This is an object of the present invention as described below.
The following patents show belt support structures having some pertinence to the invention: U.S. Pat. Nos. 6,533,108, 6,523,679, 6,296,111, 5,803,687, 5,788,056, 5,328,020, 5,186,314, 5,111,929, 4,932,516, 4,325,480, 4,013,167 and 3,826,352. Of these patents, Ledingham U.S. Pat. No. 6,533,108 shows use of a clip to secure a wear strip in a conveyor system. Manchester U.S. Pat. No. 6,523,679 shows wear strips that can be installed and removed without the use of tools in a conveyor system. U.S. Pat. No. 5,803,687 of Ledingham shows details of a clip used to hold a guide rail of a conveyor system. Andersson U.S. Pat. No. 4,932,516 discloses retrofitting of longitudinal support slats in a trough shaped conveyor belt.
The invention presents a very cost-effective, fast procedure to add further support rails to an existing spiral system. The invention can be applied to either metal belts or plastic belts, although in general its application is more critical in plastic belts with plastic connecting rods not designed to carry a load over a wide span.
The additional support apparatus includes a series of snap-on plastic brackets, to be snapped over existing cantilevered bars that extend horizontally inwardly at intervals to support the belt. These brackets, identified as cantilever clamp flanges or cantilever rail supports herein, form channels which engage with rail members that are in sections securable together around the helical path, to adjustable length. A U-shaped wear strip, preferably continuous, is placed down over the rails after they are assembled and supported by the plastic brackets on the cantilevered rods. This assembly can be accomplished without removal of the belt, which can be lifted in place sufficiently to assemble the intermediate support components. It can also be added prior to a new modular plastic belt installation, often replacing a metal conveyor belt.
In one broad aspect the invention encompasses addition of an intermediate rail in a spiral belt system by use of cantilever rail supports engaged on cantilevered support bars, with the new rail secured to the rail supports.
It is thus among the objects of the invention to provide a method and means for efficient addition of further, intermediate support rails to a spiral conveyor belt system, with or without removal of the belt or disassembly of the spiral system. This and other objects, advantages and features of the invention will be apparent from the following description, considered along with the accompanying drawings.